A federal grand jury looking into last year’s death of Kendrick Johnson, the Lowndes County high school student found in a wrestling mat, has reportedly subpoenaed some of his former classmates.

CNN, citing sources who have not been confirmed by The Atlanta Journal-Constitution, reported Thursday that some current students at Lowndes High as well as some current and former students at nearby Valdosta High School were among those seen entering the federal courthouse in Macon where the grand jury is meeting.

Johnson’s body was found Jan. 11, 2013, in a rolled-up wrestling mat in the gymnasium of Lowndes High. The case has drawn nationwide interest and has been a hot topic on websites, talk shows and social media.

Investigators ruled his death accidental, but Johnson’s parents and their attorneys believe his death was a homicide. The official police explanation is that Johnson died after he reached into the upright wrestling mat for a shoe, got stuck and suffocated.